Amorphous aluminum alloys are disclosed in Japanese Patent Laying-Open Gazette No. 1-275732, Japanese Patent Laying-Open Gazette No. 64-47831 and Japanese Patent Publication Gazette No. 1-127641, for example. The amorphous aluminum alloys disclosed in these Japanese Patent Publications contain La, or Nb, Ta, Hf, Y and the like as essential alloy components. An Al-Si-X alloy and an Al -Ce-X alloy are described in Transactions of the Japan Institue of Metals, Vol. 28, No. 12, p. 968.
The amorphous alloys disclosed in the aforementioned prior art examples are prepared by a super-rapid solidification method in most cases. According to another method an amorphous alloy can be prepared by a mechanical alloying method. In addition to the aforementioned two methods, a vapor phase deposition method, an electrolytic deposition method, an electron beam irradiation method, an extra-high pressure method and the like are known as methods for obtaining amorphous alloys. However, these methods have not yet been industrialized due to considerable practical limitations.
An amorphous alloy prepared by the super-rapid solidification method or the mechanical alloying method has not satisfied both, mechanical and economical properties. In other words, an amorphous alloy having excellent mechanical properties contains high-priced elements. An amorphous alloy containing only low-priced elements has inferior mechanical properties. An amorphous alloy is crystallized by heating. If the crystallization temperature of the amorphous alloy is too low, it is impossible to perform a sufficient warm solidification of the alloy powder. Also with a view to actual use, it is difficult to use such an amorphous alloy having a low crystallization temperature since the upper limit of the available temperatures is lowered.